Well, the rendering problem can be solved by using an existing game engine. Rendering is done in WebGL, and the engine abstracts away the browser-specific detai

Well, the rendering problem can be solved by using an existing game engine. Rendering is done in WebGL, and the engine abstracts away the browser-specific details. Furthermore, because of Google's dominance, not many browser engines are left in the market. Essentially all you have to do is support WebKit, Gecko, Blink, and you'll cover 99.9% of your userbase.